Thermomagnetic cycle device

ABSTRACT

A thermomagnetic cycle device includes a magnetocaloric effect element disposed between a high temperature end and a low temperature end, and a medium that that performs heat exchange with the magnetocaloric effect element. A magnetic field modulator periodically modulates an intensity of an external magnetic field so as to alternately repeat a magnetization period, during which the external magnetic field is applied to the magnetocaloric effect element, and a demagnetization period, during which the external magnetic field is annihilated. A heat transport device creates a relative movement between the magnetocaloric effect element and the medium. At least one of the magnetic field modulator and the heat transport device is configured such that a first heat exchange amount of the heat exchange during the magnetization period is different from a second heat exchange amount of the heat exchange during the demagnetization period.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on and incorporates herein by reference Japanese Patent Application No. 2019-100458 filed on May 29, 2019.

TECHNICAL FIELD

The present disclosure relates to a thermomagnetic cycle device.

BACKGROUND

Patent Literature 1 (JP 2016-109412 A) provides a thermomagnetic cycle device. In Patent Literature 1, startup of the thermomagnetic cycle device from an initial temperature is accelerated by adjustment of a reciprocating flow length. The disclosure of Patent Literature 1 is incorporated herein by reference to explain technical elements presented herein.

SUMMARY

According to at least one embodiment, a thermomagnetic cycle device includes a magnetocaloric effect element that is disposed between a high temperature end and a low temperature end and exerts a magnetocaloric effect, and a medium that exchanges heat with the magnetocaloric effect element. The thermomagnetic cycle device includes a magnetic field modulator that periodically modulates an intensity of an external magnetic field so as to alternately repeat a magnetization period, during which the external magnetic field is applied to the magnetocaloric effect element, and a demagnetization period, during which the external magnetic field is annihilated. The thermomagnetic cycle device includes a heat transport device that creates a relative movement between the magnetocaloric effect element and the medium. At least one of the magnetic field modulator and the heat transport device is configured such that a first heat exchange amount between the magnetocaloric effect element and the medium during the magnetization period is different from a second heat exchange amount between the magnetocaloric effect element and the medium during the demagnetization period.

BRIEF DESCRIPTION OF THE DRAWINGS

The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims.

FIG. 1 is a block diagram illustrating an air conditioner according to at least one first embodiment.

FIG. 2 is a plan view illustrating a cam having multiple tracks.

FIG. 3 is a waveform diagram illustrating changes in flow of heat medium and magnetic field.

FIG. 4 is a graph illustrating a temperature distribution of a MHP device.

FIG. 5 is a graph illustrating a temperature distribution of a MHP device.

FIG. 6 is a flowchart illustrating a control process,

FIG. 7 is a block diagram illustrating a thermal apparatus according to at least one embodiment.

FIG. 8 is a waveform diagram illustrating changes in flow of heat medium and magnetic field.

FIG. 9 is a block diagram illustrating a thermal apparatus according to at least one embodiment.

FIG. 10 is a waveform diagram illustrating changes in flow of heat medium and magnetic field.

FIG. 11 is a block diagram illustrating a thermal apparatus according to at least one embodiment.

FIG. 12 is a flowchart illustrating a control process.

FIG. 13 is a waveform diagram illustrating a temperature change of a MHP device.

FIG. 14 is a block diagram illustrating a thermal apparatus according to at least one embodiment.

FIG. 15 is a block diagram illustrating a thermal apparatus according to at least one embodiment,

FIG. 16 is a block diagram illustrating a thermal apparatus according to at least one embodiment.

FIG. 17 is a flowchart illustrating a control process,

FIG. 18 is a waveform diagram illustrating a temperature change of a MHP device.

FIG. 19 is a flowchart of a thermal apparatus according to at least one embodiment.

FIG. 20 is a block diagram illustrating a MHP device according to at least one embodiment.

FIG. 21 is a cross-sectional view taken along a line XXI-XXI of FIG. 20.

FIG. 22 is a waveform diagram illustrating a magnetic field strength and a rotation angle.

DETAILED DESCRIPTION

According to an aspect of the present disclosure, a thermomagnetic cycle device includes a magnetocaloric effect element that is disposed between a high temperature end and a low temperature end and exerts a magnetocaloric effect, and a medium that exchanges heat with the magnetocaloric effect element. The thermomagnetic cycle device includes a magnetic field modulator that periodically modulates an intensity of an external magnetic field so as to alternately repeat a magnetization period, during which the external magnetic field is applied to the magnetocaloric effect element, and a demagnetization period, during which the external magnetic field is annihilated. The thermomagnetic cycle device includes a heat transport device that creates a relative movement between the magnetocaloric effect element and the medium. At least one of the magnetic field modulator and the heat transport device is configured such that a first heat exchange amount between the magnetocaloric effect element and the medium during the magnetization period is different from a second heat exchange amount between the magnetocaloric effect element and the medium during the demagnetization period.

According to the disclosed thermomagnetic cycle device, the first heat exchange amount between the magnetocaloric effect element and the medium during the magnetization period is different from the second heat exchange amount between the magnetocaloric effect element and the medium during the demagnetization period. The difference between the first heat exchange amount and the second heat exchange amount changes a temperature of the magnetocaloric effect element. Therefore, a temperature change of the magnetocaloric effect element is accelerated. The acceleration of the temperature change of the magnetocaloric effect element contributes to reduction in startup time from a start of the thermomagnetic cycle device until a target heat output is obtained.

In one aspect, the first heat exchange amount may be larger than the second heat exchange amount (Q1>Q2). When the temperature of the magnetocaloric effect element decreases during the demagnetization period due to the magnetocaloric effect, a cold storage operation is provided. The cold storage operation accelerates decrease in temperature of the magnetocaloric effect element.

In one aspect, the first heat exchange amount may be smaller than the second heat exchange amount (Q1<Q2). When the temperature of the magnetocaloric effect element increases during the magnetization period due to the magnetocaloric effect, a heat storage operation is provided. The heat storage operation accelerates increase in temperature of the magnetocaloric effect element.

Embodiments of the present disclosure will be described hereinafter referring to drawings. In the embodiments, a part that corresponds to a matter described in a preceding embodiment may be assigned with the same reference numeral, and redundant explanation for the part may be omitted. When only a part of a configuration is described in an embodiment, another preceding embodiment may be applied to the other parts of the configuration. The parts may be combined even if it is not explicitly described that the parts can be combined. The embodiments may be partially combined even if it is not explicitly described that the embodiments can be combined, provided there is no harm in the combination.

Several embodiments will be described with reference to the drawings. In some embodiments, parts which are functionally and/or structurally corresponding and/or associated are given the same reference numerals, or reference numerals with different hundreds digit or higher digits. For corresponding parts and/or associated parts, additional explanations can be made to the description of other embodiments.

First Embodiment

FIG. 1 shows an air conditioner 1 according to a first embodiment. The air conditioner 1 is one of thermal devices. The air conditioner 1 includes a magnetocaloric heat pump device 2, also referred to as a MHP (Magneto-caloric effect Heat Pump) device 2. The MHP device 2 provides a thermomagnetic cycle device.

In this specification the term “heat pump device” is used in a broad sense. That is, the term “heat pump device” includes both a device utilizing cold energy obtained by the heat pump device and a device utilizing hot energy obtained by the heat pump device. Devices that utilize cold energy may also be referred to as refrigeration cycle devices. Hence, in this specification the term “heat pump device” is used as a concept encompassing a refrigeration cycle device.

The MHP device 2 is configured to generate a temperature difference between a high temperature end HT and a low temperature end LT. The air conditioner 1 includes a high-temperature heat exchanger 3 and a low-temperature heat exchanger 4. The high-temperature heat exchanger 3 is provided at the high temperature end HT. The low-temperature heat exchanger 4 is provided at the low temperature end LT. The air conditioner 1 includes an apparatus that extracts a thermal output from the MHP device 2. One of the apparatus may be the high-temperature heat exchanger 3 that utilizes high temperature obtained at the high temperature end HT of the MHP device 2. The high-temperature heat exchanger performs heat exchange between the high temperature end HT and a medium such as air. The high-temperature heat exchanger 3 is used mainly for heat release. The high-temperature heat exchanger 3 is disposed in a compartment of a vehicle, and heats air via heat exchange with air-conditioning air. The high-temperature heat exchanger 3 is one of components of a high temperature system, One of output apparatus may be the low-temperature heat exchanger 4 that utilizes low temperature obtained at the low temperature end LT of the MHP device 2. The low-temperature heat exchanger 4 performs heat exchange between the low temperature end LT and a medium such as air. The low-temperature heat exchanger 4 is used mainly for heat absorption. The low-temperature heat exchanger 4 is disposed outside the vehicle, and exchanges heat with outside air. The low-temperature heat exchanger 4 is one of components of a low temperature system.

The MHP device 2 includes a power source 5 for driving the MHP device 2. The MHP device 2 is, for example, driven and rotated by the power source 5. The power source 5 is an only power source 5 for the MHP device 2. The power source 5 is provided by a rotary device such as an electric motor or an internal combustion engine. An example of the power source 5 is an electric motor driven by a battery mounted on the vehicle.

The MHP device 2 comprises a housing 6. The housing 6 defines a working chamber through which a medium can flows for heat transfer. One working chamber extends in an axial direction of the housing 6. One working chamber has openings at opposite ends of the housing 6 in the axial direction.

The MHP device 2 includes a magnetocaloric effect element 7, hereinafter called a MCE element 7. The MCE element 7 is disposed between the high temperature end HT and the low temperature end LT. The MCE element 7 exerts a magnetocaloric effect. The MCE element 7 is fixed and supported in the housing 6. The MCE element 7 is positioned inside the working chamber. The MCE element 7 has an elongated shape extending along the axial direction of the housing 6.

The MHP device 2 uses the magnetocaloric effect of the MCE element 7. The MHP device 2 generates the high temperature end HT and the low temperature end LT by the MCE element 7. The MCE element 7 is disposed between the high temperature end HT and the low temperature end LT.

The MCE element 7 performs heat radiation and heat absorption in response to a change in intensity of an external magnetic field. The MCE element 7 radiates heat by generation of the external magnetic field, and absorbs heat by annihilation of the external magnetic field. The generation of the external magnetic field causes electron spins in the MCE element 7 to be aligned in a direction of the magnetic field, and accordingly, the MCE element 7 decreases in magnetic entropy and radiates heat. As a result, the MCE element 7 increases in temperature. On the other hand, the annihilation of the external magnetic field causes the electron spins to become disordered, and accordingly, the MCE element 7 increases in magnetic entropy and absorbs heat. As a result, the MCE element 7 decreases in temperature.

The MCE element 7 is made of a magnetic material that exerts a high magnetocaloric effect in a range of ordinary temperature. For example, gadolinium-based materials or lanthanum-iron-silicon compounds can be used. Also, mixtures of manganese, iron, phosphorus and germanium can be used. An element, which absorbs heat by generation of the external magnetic field and radiates heat by annihilation of the external magnetic field, can be used as the MCE element 7.

The MCE element 7 includes multiple partial elements which are connected in series. The MCE element 7 is provided by cascade connection and is also called a cascade connection element. The multiple partial elements exert magnetocaloric effects at high efficiency in different temperature ranges. The multiple partial elements are arranged so as to divide a temperature difference between the high temperature end HT and the low temperature end LT.

The MCE element 7 is positioned so as to exchange heat with a medium 8 that conveys heat. In other words, the medium 8 exchanges heat with the MCE element 7. The working chamber is filled with the medium 8. The medium 8 provides a heat storage element which stores and transfers heat. The MCE element 7 is elongated along a flow direction of the medium 8. The medium 8 is called a primary medium. The primary medium can be provided by a fluid such as antifreeze, water, oil and the like. The housing 6 and the MCE element 7 provide an element bed.

The MHP device 2 includes a magnetic field modulator 11 (MGMD) and a heat transport device 21 (THMD) for the MCE element 7 functioning as an element of an AMR cycle (Active Magnetic Refrigeration Cycle). The magnetic field modulator 11 includes a magnetic field source. The magnetic field source may be a permanent magnet, an electromagnet, or a combination of a permanent magnet and an electromagnet.

The magnetic field modulator 11 provides the MCE element 7 with a magnetic field that periodically changes. The MCE element 7 is disposed in the magnetic field and exerts a magnetocaloric effect. The magnetic field modulator 11 gives the external magnetic field to the MCE element 7 and increases or decreases the strength of the external magnetic field. The magnetic field modulator 11 periodically switches between a magnetization state in which the MCE element 7 is in a strong magnetic field and a demagnetization state in which the MCE element 7 is in a weak magnetic field or a zero magnetic field. The magnetic field modulator 11 includes a movable mechanism that periodically changes a distance between the MCE element 7 and the magnetic field source. The movable mechanism moves one of the MCE element 7 and the magnetic field source with respect to the other one. The magnetic field modulator 11 periodically modulates the strength of the external magnetic field so as to alternately repeat a magnetization period MGPR, during which the external magnetic field is given to the MCE element 7, and a demagnetization period DEMG, during which the external magnetic field is annihilated.

In FIG. 3, a waveform MG shows a magnetic field. The magnetic field modulator 11 modulates the external magnetic field so as to periodically repeat the magnetization period MGPR and the demagnetization period DEMG. The magnetization period MGPR is a period in which the MCE element 7 is placed in a strong external magnetic field. The magnetization period MGPR includes an increasing period MG+ in which the strength of the magnetic field increases. The increasing period MG+ starts at time t1 and ends at time t2. The magnetization period MGPR includes a saturation period in which the magnetic field is saturated in a strong state. The demagnetization period DEMG is a period in which the MCE element 7 is placed in an external magnetic field weaker than that of the magnetization period MGPR. The demagnetization period DEMG includes a decreasing period MG− in which the strength of the magnetic field decreases. The decreasing period MG− starts at time t3 and ends at time t4. The demagnetization period DEMG includes a saturation period in which the magnetic field is saturated in a weak state. In this embodiment, the magnetization period MGPR and the demagnetization period DEMG are equal in length. The increasing period MG+ and the decreasing period MG− are equal in length. Alternatively, the magnetization period MGPR and the demagnetization period DEMG may be different in length. The increasing period MG+ and the decreasing period MG− may be different in length.

In FIG. 1, the heat transport device 21 reciprocally generates relative movement between the MCE element 7 and the medium 8. The heat transport device 21 causes the medium 8 to flow reciprocally along the MCE element 7 and exchange heat with the MCE element 7. The heat transport device 21 causes the medium 8 to flow reciprocally in synchronization with change in magnetic field. The heat transport device 21 moves the medium 8 in the axial direction (left and right direction in FIG. 1) in synchronization with heat radiation and heat absorption by the magnetocaloric effect of the MCE element 7. The heat transport device 21 causes relative and reciprocal movement between the medium 8 and the MCE element 7. In this present embodiment, the reciprocal movement is realized by the reciprocating flow of the medium 8. A medium flowing through the high-temperature heat exchanger 3 and the low-temperature heat exchanger 4 is the medium 8. The medium flowing through the high-temperature heat exchanger 3 and the low-temperature heat exchanger 4 may be a secondary medium that exchanges heat with the medium 8.

The heat transport device 21 includes a pump 31 that pumps the medium 8. The heat transport device 21 includes a positive displacement pump 31 that provides the reciprocating flow. The pump 31 shown in the drawings produces the reciprocating flow of the medium 8 by multiple pistons which are driven to be complementary with each other. The heat transport device 21 includes a link mechanism 32 and a cam mechanism 33 for driving the multiple pistons. The cam mechanism 33 provides a converter that converts a rotational force supplied from the power source 5 into a reciprocating motion. The link mechanism 32 transmits the reciprocating motion supplied from the cam mechanism 33 to the multiple pistons. The cam mechanism 33 includes a cam follower 41 and a cam rotor 42. The cam follower 41 moves along a cam profile 43 provided on the cam rotor 42. The cam profile 43 includes multiple tracks. The cam follower 41 is configured to select one of the multiple tracks. In other words, the cam follower 41 is configured to switch the multiple tracks.

In FIG. 2, two tracks 44, 45 on the cam profile 43 are shown. The two tracks 44, 45 are formed concentrically. The cam follower 41 is capable of selecting the track 44 or the track 45. The track 44 produces a first cam stroke waveform in which an upstroke and a downstroke are symmetrical. The track 45 produces a second cam stroke waveform in which an upstroke and a downstroke are asymmetrical. The first cam stroke waveform and the second cam stroke waveform generate different flow waveforms of the medium 8. In other words, a second flow waveform generated by the second cam stroke waveform is different from a first flow waveform generated by the first cam stroke waveform. The first flow waveform and the second flow waveform cause heat storage or cold storage in the MCE element 7. The heat storage amount or the cold storage amount in the MCE element 7 by the second flow waveform is larger than the heat storage amount or the cool storage amount in the MCE element 7 by the first flow waveform. The MHP device 2 utilizes the difference in heat storage amount or cold storage amount to accelerate a startup, that is, to shorten a startup time.

In FIG. 1, the heat transport device 21 includes a switch (SW) 34 that controls a position of the cam follower 41 so as to select the track 44 or the track 45. The switch 34 can be provided by an electric motor or a servo motor.

The MHP device 2 includes a controller (CTR) 35. The controller 35 controls at least the power source 5. The controller 35 controls a number of rotations of the power source 5. The controller 35 controls the switch 34. In addition, the controller 35 controls functions of the air conditioner 1. The controller 35 controls, for example, a flow rate of air sent to the high-temperature heat exchanger 3 and/or the low-temperature heat exchanger 4.

The controller 35 is an electronic control unit. The controller 35 provides a control system for the thermomagnetic cycle device. The controller 35 has at least one arithmetic processing unit (CPU) and at least one memory device (MMR) as a storage medium for storing programs and data. The control system is provided by a microcomputer comprising a computer readable storage medium. The storage medium is a non-transitional tangible storage medium that temporarily stores a computer readable program. The storage medium may be provided as a semiconductor memory, a magnetic disk, or the like. The control system may be provided by one computer or a group of computer resources linked via a data communication device. The program is executed by the control system to cause the control system to function as a device described in the present specification and to cause the control system to function to perform the methods described in the present specification.

Means and/or functions provided by the control system can be provided by software recorded in a substantive memory device and a computer that can execute the software, software only, hardware only, or some combination of them. For example, the control system can be provided by a logic called if-then-else type, or a neural network tuned by machine learning. For example, if the control system is provided by an electronic circuit that is hardware, the controller may be provided by a digital circuit or an analog circuit that includes a large number of logic circuits.

The controller in this specification may be referred to as an electronic control unit (ECU: Electronic Control Unit). The controller or the control system is provided by (a) an algorithm as a plurality of logic called an if-then-else form, or (b) a learned model tuned by machine learning, e.g., an algorithm as a neural network.

The controller is provided by a control system including at least one computer. The control system may include a plurality of computers linked by data communication devices. The computer includes at least one processor (hardware processor) that is hardware. The hardware processor can be provided by the following (i), (ii), or (iii).

(i) The hardware processor may be at least one processor core that executes a program stored in at least one memory. In this case, the computer is provided by at least one memory and at least one processor core. The processor core is called a CPU: Central Processing Unit, a GPU: Graphics Processing Unit, a RISC-CPU, or the like. The memory is also called a storage medium. The memory is a non-transitory and tangible storage medium, which non-temporarily stores a program and/or data readable by the processor. The storage medium may be a semiconductor memory, a magnetic disk, an optical disk, or the like. The program may be distributed as a single unit or as a storage medium in which the program is stored.

(ii) The hardware processor may be a hardware logic circuit. In this case, the computer is provided by a digital circuit including a number of programmed logic units (gate circuits). The digital circuit is also called a logic circuit array, for example, ASIC: Application-Specific Integrated Circuit, FPGA: Field Programmable Gate Array, SoC: System on a Chip, PGA: Programmable Gate Array, or CPLD: Complex Programmable Logic Device. The digital circuit may comprise a memory storing programs and/or data. The computer may be provided by an analog circuit. A computer may be provided by a combination of a digital circuit and an analog circuit.

(iii) The hardware processor may be a combination of the above (i) and the above (ii). (i) and (ii) are placed on different chips or on a common chip. In these cases, the part (ii) is also called an accelerator.

The controller, the signal source, and the control object provide various elements. At least some of these elements can be referred to as blocks, modules, or sections. Furthermore, elements included in the control system are referred to as functional means only when intentional.

A control units and methods described in the present disclosure may be implemented by a special purpose computer which is configured with a memory and a processor programmed to execute one or more particular functions embodied in computer programs of the memory. Alternatively, the control unit described in the present disclosure and the method thereof may be realized by a dedicated computer configured as a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described in the present disclosure may be realized by one or more dedicated computer, which is configured as a combination of a processor and a memory, which are programmed to perform one or more functions, and a processor which is configured with one or more hardware logic circuits. The computer programs may be stored, as instructions to be executed by a computer, in a tangible non-transitory computer-readable medium.

FIG. 3 is a waveform diagram showing operations of multiple parts of the MHP device 2. The cam profile 43 defines a stroke ST of the cam follower 41. The track 44 provides a stroke ST44 of the cam follower 41. The track 45 provides a stroke ST45 of the cam follower 41. The stroke ST is transmitted to the pump 31 by the link mechanism 32. The pump 31 provides the reciprocating flow of the medium 8. The stroke ST defines a flow rate FR.

The stroke ST44 creates a flow rate waveform FR44 shown by a dash line. The flow rate waveform FR44 indicates that the medium 8 flows in one direction during the magnetization period MGPR while the medium 8 flows in another direction during the demagnetization period DEMG. The one direction is a direction from the low temperature end LT toward the high temperature end HT. The other direction is a direction from the high temperature end HT to the low temperature end LT. The flow rate waveform FR44 is provided in a normal operation mode. In the normal operation mode, a change within one cycle is symmetrical in both magnetic field waveform and flow rate waveform. The normal operation mode is also called an isothermal cycle mode or an adiabatic cycle mode.

FIG. 4 shows a temperature distribution at the time of startup according to the flow rate waveform FR44. The horizontal axis represents a length L of the MCE element 7 in a cascade connection direction. The vertical axis represents a temperature TEMP of the MCE element 7. The MHP device 2 at the time of startup is considered. The temperature of the MHP device 2 is assumed to be stable at an initial temperature Ti before starting up. The initial temperature Ti may be an outside air temperature. At the time of startup, a temperature distribution in the MHP device 2 is assumed to be stable at the initial temperature Ti as shown by a dash line.

A temperature change in a startup period of the MHP device 2 according to the flow rate waveform FR44 is considered. The startup period of the MHP device 2 after the MHP device 2 has been left under the outside air temperature for a long period of time is considered. First, an initial partial element that exerts the magnetocaloric effect at the initial temperature Ti repeats heat radiation and heat absorption. This creates a temperature gradient in the initial partial element. As an operation of the MHP device 2 continues, a range of the temperature gradient expands. The number of the partial elements exerting the magnetocaloric effect increases.

Further, in addition to the heat radiation and the heat absorption due to the MCE element 7, disturbance heat is applied to the MCE element 7. The disturbance heat includes, for example, a heat capacity of the MHP device 2, heat generation from the power source 5, and heat generation from an electric circuit. The disturbance heat hinders a growth of the temperature gradient in a direction toward the low temperature end LT. The disturbance heat assists a growth of the temperature gradient in a direction toward the high temperature end HT. As a result, in the startup period in which the temperature gradient grows, a speed at which the temperature gradient grows toward the high temperature end HT is faster than a speed at which the temperature gradient grows toward the low temperature end LT. In other words, in the startup period, a temperature increase width dTh44 that spreads from the initial temperature Ti toward the high temperature end HT is larger than a temperature decrease width dTc44 that spreads from the initial temperature Ti toward the low temperature end LT (dTh44>dTc44). From another viewpoint, in the startup period, an activation length extending from the initial partial element toward the high temperature end HT is longer than an activation length extending from the initial partial element toward the low temperature end LT. According to the flow rate waveform FR44, it takes a long time for both the high temperature end HT and the low temperature end LT of the MHP device 2 to reach target temperatures TH and TL. In other words, a startup time is long according to the flow rate waveform FR44.

In most cases, the air conditioner 1 and the MHP device 2 use a cold energy outputted from the low temperature end LT. The temperature of the cold energy is lower than the outside air temperature. Therefore, a difference (TH-Ti) between the initial temperature Ti and the target temperature TH at the high temperature end HT is smaller than a difference (Ti-TL) between the initial temperature Ti and the target temperature TL at the low temperature end LT (i.e., TH-Ti<Ti-TL). Such a use temperature condition of the MHP device 2 also further lengthens the startup time by the flow rate waveform FR44.

In FIG. 3, the stroke ST45 creates a flow rate waveform FR45 shown by a solid line. The flow rate waveform FR45 indicates that the medium 8 flows in one direction during the magnetization period MGPR while the medium 8 flows in another direction during the demagnetization period DEMG. The flow rate waveform FR45 is provided in an acceleration operation mode. In the acceleration operation mode, a change within one cycle is asymmetrical in the magnetic field waveform, the flow rate waveform or both the magnetic field waveform and the flow rate waveform.

The flow rate waveform FR45 has a reduction period REPR in which a flow rate of the medium 8 is reduced in the demagnetization period DEMG. The largest flow rate FR45 m of the flow rate waveform FR45 is larger than the largest flow rate FR44 m of the flow rate waveform FR44. A flow rate in the reduction period REPR is smaller than a flow rate in the other remaining period of the demagnetization period DEMG. In this embodiment, the flow rate in the remaining period of the demagnetization period DEMG is the largest flow rate FR45 m. The flow rate in the reduction period REPR is smaller than the largest flow rate FR45 m of the flow rate waveform FR45. In the present embodiment, the flow rate in the reduction period REPR is 0 (zero). The integral of flow rate provided by the flow rate waveform FR44 and the integral of flow rate provided by the flow rate waveform FR45 are set to be equal.

The reduction period REPR is provided at the beginning of the demagnetization period DEMG. The reduction period REPR is provided so as to at least partially overlap the decreasing period MG−. In the present embodiment, the reduction period REPR completely overlaps the decreasing period MG−. The reduction period REPR starts at time t3 and ends at time t4.

In the reduction period REPR, the external magnetic field applied to the MCE element 7 is annihilated. In the reduction period REPR, the temperature of the MCE element 7 decreases. Particularly. In the decreasing period MG−, the external magnetic field applied to the MCE element 7 is annihilated. In the decreasing period MG−, the temperature of the MCE element 7 decreases. During the reduction period REPR, the low temperature of the MCE element 7 acts to reduce the temperature of the MCE element 7 without being carried away by the medium 8. In other words, the MCE element 7 stores cold energy. Furthermore, a heat exchange efficiency between the MCE element 7 and the medium 8 may decrease during a period of the largest flow rate FR45 m following the reduction period REPR. In this case, cold storage in the reduction period REPR is likely to be maintained.

Therefore, the heat transport device 21 has the reduction period REPR in which an amount of heat exchange between the MCE element 7 and the medium 8 is reduced in the demagnetization period DEMG. The heat transport device 21 provides the reduction period REPR by stopping flow of the medium 8 at the beginning of the demagnetization period DEMG, As a result, the heat transport device 21 is set so that a first heat exchange amount Q1 between the MCE element 7 and the medium 8 during the magnetization period MGPR is larger than a second heat exchange amount Q2 between the MCE element 7 and the medium 8 during the demagnetization period DEMG (i.e., Q1>Q2), The heat transport device 21 has the normal operation mode in which the first heat exchange amount Q1 and the second heat exchange amount Q2 are equal (i.e., Q1=Q2). Further, the heat transport device 21 is configured to be switchable between the acceleration operation mode and the normal operation mode.

FIG. 5 shows a temperature distribution at the time of startup according to the flow rate waveform FR45, The conditions are the same as in FIG. 4. A temperature change in a startup period of the MHP device 2 according to the flow rate waveform FR45 is considered.

Also for the flow rate waveform FR45, the temperature gradient gradually widens. Further, the disturbance heat is applied to the MCE element 7. Further, according to the flow rate waveform FR45, the MCE element 7 stores cold energy. The temperature drop due to this cold storage at least partially offsets the temperature rise due to the disturbance heat. The temperature drop due to the cold storage hinders a growth of the temperature gradient in a direction toward the high temperature end HT. The temperature drop due to the cold storage assists a growth of the temperature gradient in a direction toward the low temperature end LT.

The temperature drop due to cold storage of the MCE element 7 assists the growth of the temperature gradient in the direction toward the low temperature end LT. In this case, the growth speed of the temperature gradient in the high temperature direction may still exceed the growth speed of the temperature gradient in the low temperature direction. Nevertheless, the growth speed of the temperature gradient generated by the flow rate waveform FR45 in the low temperature direction is higher than the growth speed of the temperature gradient generated by the flow rate waveform FR44 in the low temperature direction. As a result, the startup time is shortened by the flow rate waveform FR45.

In another mode, the growth speed of the temperature gradient in the high temperature direction may become equivalent to the growth speed of the temperature gradient in the low temperature direction. The two growth speeds may become equal. For example, in the startup period, the temperature increase width dTh45 may become equal to the temperature decrease width dTc45 (i.e., dTh45=dTc45). In this case, the startup time is clearly shortened.

In another mode, the growth speed of the temperature gradient in the high temperature direction may be smaller than the growth speed of the temperature gradient in the low temperature direction. For example, in the startup period, the temperature increase width dTh45 may become smaller than the temperature decrease width dTc45 (i.e., dTh45<dTc45). In this case, the startup time is significantly shortened. Therefore, the flow rate waveform FR45 including the reduction period REPR realizes a shorter startup time than the flow rate waveform FR44 that does not include the reduction period REPR. Further, the flow rate waveform FR45 may provide the temperature decrease width dTc45 that is higher than or equal to the temperature increase width dTh45 during the startup period (i.e., dTh45≤dTc45). In other words, the cooldown operation time of the MHP device 2 is shortened.

FIG. 6 shows a control process 180 for switching between the flow rate waveform FR44 and the flow rate waveform FR45. The control process 180 is executed by the controller 35. At step 181, the controller 35 determines whether an elapsed time timer from a startup of the MHP device 2 exceeds a preset threshold time Tth0. Step 181 provides a timer process. When the elapsed time timer does not exceed the threshold time Tth0, the process proceeds to step 182. At step 182, the controller 35 selects the track 45 by the switch 34. As a result, the flow rate waveform FR45 is provided. Accordingly, the startup of the MHP device 2 is accelerated. Step 182 provides the acceleration operation mode. The acceleration operation mode is also called a cold storage operation mode. The acceleration operation mode is also called a startup operation mode, a temperature-increase reduction mode, and a temperature-decrease acceleration mode. When the elapsed time timer exceeds the threshold time Tth0, the process proceeds to step 183. At step 183, the controller 35 selects the track 44 by the switch 34. As a result, the flow rate waveform FR44 is provided. Accordingly, the MHP device 2 is stably operated. Step 183 provides the normal operation mode. The controller 35 uses the timer to define a period of the acceleration operation mode which is executed before the normal operation mode.

In this embodiment, the reduction period REPR is provided only within the demagnetization period DEMG. In addition, the reduction period REPR may be provided within the magnetization period MGPR. The reduction period REPR (0) within the demagnetization period DEMG is set longer than the reduction period REPR (M) within the magnetization period MGPR, In this case, the temperature decrease width dTc45 is larger than or equal to the temperature increase width dTh45. As a result, the cooldown operation time of the MHP device 2 is shortened.

In this embodiment, the reduction period REPR is provided only within the demagnetization period DEMG. Alternatively, the reduction period REPR may be provided only within the magnetization period MGPR. The reduction period REPR (M) within the magnetization period MGPR may be set longer than the reduction period REPR (D) within the demagnetization period DEMG. In this case, the MCE element 7 stores heat energy in the reduction period REPR. Therefore, the growth speed of the temperature gradient in the high temperature direction is accelerated. Such an alternative modified example may be suitable for an application utilizing a high temperature provided from the high temperature end HT. For example, it may be suitable when the MHP device 2 is used for air heating. The reduction period REPR within the magnetization period MGPR contributes to shortening the startup time that elapses before the temperature of the high temperature end HT reaches its target temperature TH. In other words, the warmup operation time of the MHP device 2 is shortened.

According to the embodiment described above, the first heat exchange amount Q1 between the MCE element 7 and the medium 8 in the magnetization period MGPR is different from the second heat exchange amount Q2 between the MCE element 7 and the medium 8 in the demagnetization period DEMG, The heat exchange amounts Q1, Q2 are set by the magnetic field modulator 11 and/or the heat transport device 21. As a result, the startup time required for the MHP device 2 to provide a target heat output is shortened.

Second Embodiment

This embodiment is a modification based on the preceding embodiment. In the above embodiment, the different heat exchange amounts are provided by switching the flow rate waveform. Alternatively, different heat exchange amounts may be provided by switching a magnetic field waveform.

As shown in FIG. 7, a cam mechanism 33 has a cam profile 243. The cam profile 243 includes only one track 44. A magnetic field modulator 11 can adjust a change waveform of the magnetic field applied to a MCE element 7. The magnetic field modulator 11 additionally or alternatively includes an electromagnet (EMG) 211 a in order to make the magnetic field variable. The magnetic field modulator 11 provides at least two magnetic field waveforms. A MHP device 2 comprises a switch 236. The switch 236 is provided by a drive circuit that excites the electromagnet 211 a of the magnetic field modulator 11. The switch 236 switches the magnetic field waveform. The MHP device 2 includes a controller 35. The controller 35 controls the switch 236. The controller 35 switches the magnetic field waveform by, for example, executing the control process 180 of the preceding embodiment. In the control process 180, the flow rate waveform FR44 is replaced with the magnetic field waveform CMP, and the flow rate waveform FR45 is replaced with the magnetic field waveform EMB2.

FIG. 8 shows change in flow rate of a medium 8 and change in magnetic field MG. The heat transport device 21 provides a fixed flow rate waveform FR44. The magnetic field modulator 11 provides an increasing period MG+ and a decreasing period MG−. The increasing period MG+ is longer than the decreasing period MG− (i.e., MG+>MG−). A difference between the increasing period MG+ and the decreasing period MG− may be set such that a growth speed of a temperature gradient in a low temperature direction is accelerated against disturbance heat. The increasing period MG+ occupies 50% or more of a magnetization period MGPR. The decreasing period MG− is less than 50% of the demagnetization period DEMG. Since the increasing period MG+ is lengthened, an increase rate of the external magnetic field applied to the MCE element 7 is reduced. The magnetic field waveform EMB2 of this embodiment increases slowly and decreases quickly. As a result, the MCE element 7 slowly generates heat as compared with the magnetic field waveform CMP of a comparative example indicated by a dash line in FIG. 8. A predetermined amount of the medium 8 flows past the MCE element 7 before the MCE element 7 radiates heat. Therefore, a heat exchange amount in the magnetization period MGPR is reduced as compared with a heat exchange amount in the demagnetization period DEMG. As a result, the MHP device 2 decelerates the temperature rise and accelerates the temperature fall. As a result, the cooldown operation time of the MHP device 2 is shortened.

In addition, in an application utilizing high temperature provided from the high temperature end HT, the increasing period MG+ is set to be shorter than the decreasing period MG− (i.e., MG+<MG−), or the increasing period MG+ is set to be equal to the decreasing period MG−(i.e., MG+=MG−). In these cases, a warmup operation time of the MHP device 2 is shortened. When the increasing period MG+ is set shorter than the decreasing period MG−, the warmup operation time of the MHP device 2 is significantly shortened.

According to the present embodiment, the heat exchange amount between the MCE element 7 and the medium 8 in the magnetization period MGPR is different from the heat exchange amount between the MCE element 7 and the medium 8 in the demagnetization period DEMG. The magnetic field modulator 11 is set so that a first heat exchange amount Q1 between the MCE element 7 and the medium 8 during the magnetization period MGPR is larger than a second heat exchange amount Q2 between the MCE element 7 and the medium 8 during the demagnetization period DEMG (i.e., Q1>Q2). As a result, the startup time required for the MHP device 2 to provide a target heat output is shortened.

Third Embodiment

This embodiment is a modification based on the preceding embodiment. In the above embodiments, the flow rate waveform or the magnetic field waveform is switched. Alternatively, different heat exchange amounts may be provided by switching both the flow rate waveform and the magnetic field waveform.

In FIG. 9, a MHP device 2 includes the cam profile 43 of the first embodiment and the magnetic field modulator 11 of the second embodiment. The MHP device 2 includes a controller 35 that controls both the switch 34 and the switch 236, The controller 35 switches both the flow rate waveform and the magnetic field waveform by, for example, executing the control process 180 of the preceding embodiment. In the control process 180, both the flow rate waveform FR45 and the magnetic field waveform EMB2 are provided at step 182, and both the flow rate waveform FR44 and the magnetic field waveform CMP are provided at step 183.

In FIG. 10, in the present embodiment, both the flow rate waveform FR45 and the magnetic field waveform EMB2 are provided in a cold storage operation during a startup period. In a normal operation after startup, both the flow rate waveform FR44 and the magnetic field waveform CMP are provided, According to the present embodiment, the heat exchange amount between the MCE element 7 and the medium 8 in the magnetization period MGPR is different from the heat exchange amount between the MCE element 7 and the medium 8 in the demagnetization period DEMG. The magnetic field modulator 11 and the heat transport device 21 are set so that a first heat exchange amount Q1 between the MCE element 7 and the medium 8 during the magnetization period MGPR is larger than a second heat exchange amount Q2 between the MCE element 7 and the medium 8 during the demagnetization period DEMG (i.e., Q1>Q2). As a result, the startup time required for the MHP device 2 to provide a target heat output is shortened.

Fourth Embodiment

This embodiment is a modification based on the preceding embodiment. In the above-described embodiments, the controller 35 defines the period of the accelerated operation (cold storage operation) by using a timer. Alternatively, the period of the accelerated operation can be defined based on an observation value such as temperature information.

In FIG. 11, a MHP device 2 includes a temperature sensor 437 that observes a temperature of a medium 8 at a low temperature end LT. An observation signal TEMP1 by the temperature sensor 437 is input to the controller 35. An observation temperature TEMP1 is an example of the observation information related to a temperature of a MCE element 7.

FIG. 12 shows a control process 480 for switching between the flow rate waveform FR44 and the flow rate waveform FR45. The control process 480 is executed by the controller 35. At step 484, the controller 35 determines an operation mode required for the MHP device 2. When the required operation mode is a cooling mode (COOL), the process proceeds to step 485. When the required operation mode is other than the cooling mode, the process ends. Step 484 provides a mode determination unit that determines whether the operation mode is the cooling mode that is suitable for the cold storage operation. In other words, step 484 provides a prevention control that prevents the cold storage operation at startup in an operation mode that is not suitable for the cold storage operation.

At step 485, the controller 35 determines whether the observation signal TEMP1 is lower than the threshold temperature Tth1. When TEMP1 is lower than Tth1, the process proceeds to step 183. When TEMP1 is not lower than Tth1, the process proceeds to step 182. Therefore, the controller 35 repeats the cold storage operation at step 182 until the observation signal TEMP1 falls below the threshold temperature Tth1. When the observation signal TEMP1 falls below the threshold temperature Tth1, the controller 35 performs the normal operation at step 183. At step 486, the controller 35 determines whether the observation signal TEMP1 is higher than a threshold temperature Tth2. When TEMP1 is higher than Tth2, the process returns to step 182. When TEMP1 is not higher than Tth2, the process returns to step 183. The threshold temperature Tth2 is higher than the threshold temperature Tth1.

As illustrated in FIG. 13, the two threshold temperatures Tth1, Tth2 provide the observation signal TEMP1 with a hysteresis characteristic. Accordingly, unwanted frequent switching between the startup operation and the normal operation can be reduced. According to the present embodiment, the period of the acceleration operation mode (cold storage operation) can be defined based on the temperature information of the low temperature end LT provided by the observation signal TEMP1. The controller 35 defines the period of the acceleration operation mode followed by the normal operation mode based on the observation temperature TEMP1 related to the temperature of the MCE element 7.

Fifth Embodiment

This embodiment is a modification based on the preceding embodiment. In the present embodiment, a period of the cold storage operation is defined based on an observation value of a temperature of a MCE element 7.

As illustrated in FIG. 14, a MHP device 2 includes a temperature sensor 538 that directly observes the temperature of a part of the MCE element 7. In the MHP device 2 that utilizes the cold storage operation, the temperature sensor 538 may be provided in the MCE element 7 adjacent to the low temperature end LT. An observation signal TEMP2 by the temperature sensor 538 is input to a controller 35. The observation signal TEMP2 is used in the controller 35 in place of the observation signal TEMP1 of the preceding embodiment. Also according to the present embodiment, the period of the cold storage operation can be defined based on the temperature information provided by the observation signal TEMP2.

Sixth Embodiment

This embodiment is a modification based on the preceding embodiment. In the above embodiment, the period of the cold storage operation is defined. Alternatively, the period of heat storage operation may be defined based on an observation value.

As illustrated in FIG. 15, a MHP device 2 includes a temperature sensor 639 that observes a temperature of a medium 8 at a high temperature end HT. An observation signal TEMP3 by the temperature sensor 639 is input to a controller 35. The MHP device 2 utilizes high temperature provided from the high temperature end HT. In the present embodiment, a switch 34 is controlled so as to shorten a startup time that elapses before the temperature of the high temperature end HT reaches its target temperature. In the present embodiment, in the acceleration operation mode, a heat storage operation is executed instead of the cold storage operation. The observation signal TEMP3 defines a period of the heat storage operation. In the present embodiment, the period of the heat storage operation that is the acceleration operation mode can be defined based on the temperature information provided by the observation signal TEMP3.

In the heat storage operation, the magnetic field modulator 11 and/or the heat transport device 21 is set so that a first heat exchange amount Q1 between a MCE element 7 and a medium 8 during a magnetization period MGPR is smaller than a second heat exchange amount Q2 between the MCE element 7 and the medium 8 during a demagnetization period DEMG (i.e., Q1<Q2). Heat generated in the MCE element 7 due to a magnetocaloric effect increases the temperature of the MCE element 7 without being carried away by the medium 8. The heat storage operation can be realized by, for example, setting a reduction period, in which the flow rate FR is reduced, within at least a part of an increasing period MG+. The heat storage operation can be realized, for example, by making the increasing period MG+ shorter than the decreasing period MG−. According to these cases, the heat exchange amount between the MCE element 7 and the medium 8 in the magnetization period MGPR is different from the heat exchange amount between the MCE element 7 and the medium 8 in the demagnetization period DEMG. A person skilled in the art can understand a method for realizing the heat storage operation based on the cold storage operation in the preceding embodiments.

Seventh Embodiment

This embodiment is a modification based on the preceding embodiment. In the above embodiment, the period of the cold storage operation or the period of the heat storage operation is defined. Alternatively, both the period of the cold storage operation and the period of the heat storage operation may be defined based on an observation value.

As shown in FIG. 16, a MHP device 2 includes both a temperature sensor 437 and a temperature sensor 639. When the MHP device 2 is used as a low temperature source by an air conditioner 1, the MHP device 2 uses low temperature provided from a low temperature end LT. When the MHP device 2 is used as a high temperature source by the air conditioner 1, the MHP device 2 uses high temperature provided from a high temperature end HT. The air conditioner 1 switches between use of the low temperature and use of the high temperature according to an operation mode. The air conditioner 1 can switch the operation mode of the MHP device 2 according to, for example, a cooling mode and a heating mode. In the present embodiment, for example, in the cooling mode, a cold storage operation is executed during a period in which an observation temperature of the temperature sensor 437 reaches to a predetermined value from an initial temperature. Accordingly, a startup time in the cooling mode can be shortened. In the present embodiment, for example, in the heating mode, a heat storage operation is executed during a period in which an observation temperature of the temperature sensor 639 reaches to a predetermined value from the initial temperature. Accordingly, a startup time in the heating mode can be shortened.

FIG. 17 shows a control process 790 executed by the controller 35. At step 791, the controller 35 selects the cooling mode (COLD) or the heating mode (HOT). In the cooling mode, the process proceeds to step 485. In the heating mode, the process proceeds to step 792. Steps 485, 183, 486, 182 are the same as in the previous embodiments. At step 792, the controller 35 determines whether an observation signal TEMP3 is higher than a threshold temperature Tth3. When TEMP3 is higher than Tth3, the process proceeds to step 793. When TEMP3 is not higher than Tth3, the process proceeds to step 795. Therefore, the controller 35 repeats the heat storage operation at step 795 until the observation signal TEMP3 rises above the threshold temperature Tth3, When the observation signal TEMP3 rises above the threshold temperature Tth3, the controller 35 performs the normal operation at step 793. At step 794, the controller 35 determines whether the observation signal TEMP3 is lower than a threshold temperature Tth4. When TEMP3 is lower than Tth4, the process returns to step 795. When TEMP3 is not lower than Tth4, the process returns to step 793. The threshold temperature Tth3 is higher than the threshold temperature Tth4.

As illustrated in FIG. 18, the two threshold temperatures Tth3, Tth4 provide the observation signal TEMP3 with a hysteresis characteristic. Accordingly, unwanted frequent switching between the startup operation and the normal operation can be reduced. The period of the heat storage operation can be defined based on temperature information of a high temperature end HT provided by the observation signal TEMP3. According to the present embodiment, the MHP device 2 includes both the cold storage operation mode and the heat storage operation mode, and can selectively switch between them. In the cold storage operation mode, a first heat exchange amount Q1 in a magnetization period MGPR is larger than a second heat exchange amount Q2 in a demagnetization period DEMG. In the heat storage operation mode, the first heat exchange amount Q1 is smaller than the second heat exchange amount Q2. As a result, the startup time can be shortened in both the cooling mode and the heating mode.

Eighth Embodiment

This embodiment is a modification based on the preceding embodiment. In the above embodiments, switching is performed between the normal operation and the cold storage operation or between the normal operation and the heat storage operation. Alternatively, the MHP device 2 may execute the cold storage operation or the heat storage operation over an entire operation period.

FIG. 19 shows a control process 880 executed by the controller 35. The control process 880 includes only step 889. Step 889 is provided by step 182 of the cold storage operation or step 795 of the heat storage operation. Also in the present embodiment, the startup time is shortened.

Ninth Embodiment

This embodiment is a modification based on the preceding embodiment. In the second embodiment and the third embodiment, the magnetic field modulator 11 includes the electromagnet 211 a. Alternatively, the magnetic field modulator 11 may include a permanent magnet that provides a magnetic field waveform EMB2.

In FIGS. 20 and 21, the MHP device 2 includes a magnetic field modulator 11. FIG. 21 shows a cross section taken along a line XXI-XXI of FIG. 20. The magnetic field modulator 11 includes a permanent magnet 911 a as a magnetic field source. The permanent magnet 911 a is rotatable. The permanent magnet 911 a is movable in a rotation direction RT. The permanent magnet 911 a is driven by a power source 5. A MCE element 7 is stationary. The permanent magnet 911 a moves relative to the MCE element 7. The permanent magnet 911 a provides a magnetization period MGPR and a demagnetization period DEMG by the relative movement. The MCE element 7 may move with respect to the permanent magnet 911 a.

A magnetization pattern of the permanent magnet 911 a is configured to give the magnetic field waveform EMB2 to the MCE element 7. The magnetization pattern can be configured by a magnetization direction of the permanent magnet 911 a or a magnetization intensity. In the illustrated example, the magnetization pattern is configured by changing the magnetization direction of the permanent magnet 911 a. The magnetization direction is also called a magnetization vector. In FIG. 21, the outline arrows indicate the magnetization directions in the permanent magnet 911 a. The distribution of the magnetization directions gradually changes along the rotation direction RT of the permanent magnet 911 a. The magnetization direction is largely inclined with respect to a radial direction at a leading portion 911 b in the rotation direction RT. The magnetization direction is slightly inclined with respect to a radial direction at a following portion 911 c in the rotation direction RT. An inclination angle of the magnetization direction with respect to the radial direction gradually decreases from the leading portion 911 b toward the following portion 911 c, The magnetization direction coincides with the radial direction in the following portion 911 c. As a result of the gradual change in magnetization direction, the strength of the magnetic field in the radial direction applied to the MCE element 7 also gradually changes.

FIG. 22 shows a relationship between the magnetic field waveform EMB2 and a rotation angle of the permanent magnet 911 a. In FIG. 22, the waveform diagram (a) shows a strength of the magnetic field MG in the radial direction in the MCE element 7 a, In FIG. 22, the cross-sectional diagram (b) shows a rotation angle of the permanent magnet 911 a at time t91. In FIG. 22, the cross-sectional diagram (c) shows a rotation angle of the permanent magnet 911 a at time t92. The strength of the magnetic field MG in the radial direction in the MCE element 7 a changes in accordance with rotation of the permanent magnet 911 a. The increasing period MG+ is longer than the decreasing period MG−. Therefore, in the increasing period MG+, a part of the medium 8 flows past the MCE element 7 without heat exchange. As a result, a heat exchange amount between the MCE element 7 and the medium 8 in a magnetization period MGPR is different from a heat exchange amount between the MCE element 7 and the medium 8 in a demagnetization period DEMG.

The disclosure in this specification, the drawings, and the like is not limited to the illustrated embodiments. The disclosure encompasses the illustrated embodiments and variations thereof by those skilled in the art. For example, the present disclosure is not limited to the combinations of components and/or elements shown in the embodiments. The present disclosure may be implemented in various combinations. The present disclosure may have additional portions which may be added to the embodiments. The present disclosure encompasses omission of the components and/or elements of the embodiments. The present disclosure encompasses the replacement or combination of components and/or elements between one embodiment and another. The disclosed technical scope is not limited to the description of the embodiment. Several technical scopes disclosed should be understood to include all modifications within the meaning and scope equivalent to the descriptions.

The disclosure in the specification, drawings and the like is not limited by the descriptions. The disclosures in the specification, the drawings, and the like encompass the technical ideas, and further extend to a wider variety of technical ideas. Therefore, various technical ideas can be extracted from the disclosure of the specification, the drawings and the like without being limited to the descriptions.

In the above embodiments, the pump 31 is adopted. Alternatively, the heat transport device 21 may include a non-volumetric pump that provides a unidirectional flow. In this case, the heat transport device 21 includes a valve mechanism for converting the unidirectional flow into a reciprocating flow. The valve mechanism can be provided by various valve mechanisms such as a rotary switching valve, or an on-off switching valve.

In the present embodiments, the flow rate in the reduction period REPR is 0 (zero). Alternatively, the flow rate in the reduction period REPR may be a predetermined reduced flow rate. However, the reduced flow rate is smaller than a flow rate in the other remaining period of the demagnetization period DEMG.

While the present disclosure has been described with reference to various exemplary embodiments thereof, it is to be understood that the disclosure is not limited to the disclosed embodiments and constructions. To the contrary, the disclosure is intended to cover various modifications and equivalent arrangements. In addition, while the various elements of the disclosure are shown in various combinations and configurations, which are exemplary, other various combinations and configurations, including more, less or only a single element, are also within the spirit of the disclosure. 

What is claimed is:
 1. A thermomagnetic cycle device comprising: a magnetocaloric effect element that is disposed between a high temperature end and a low temperature end and exerts a magnetocaloric effect; a medium that exchanges heat with the magnetocaloric effect element; a magnetic field modulator that periodically modulates an intensity of an external magnetic field so as to alternately repeat a magnetization period, during which the external magnetic field is applied to the magnetocaloric effect element, and a demagnetization period, during which the external magnetic field is annihilated; and a heat transport device that creates a relative movement between the magnetocaloric effect element and the medium, wherein at least one of the magnetic field modulator and the heat transport device is configured such that a first heat exchange amount between the magnetocaloric effect element and the medium during the magnetization period is different from a second heat exchange amount between the magnetocaloric effect element and the medium during the demagnetization period.
 2. The thermomagnetic cycle device according to claim 1, wherein the at least one of the magnetic field modulator and the heat transport device is configured such that the first heat exchange amount is larger than the second heat exchange amount.
 3. The thermomagnetic cycle device according to claim 2, wherein the heat transport device is configured to reduce heat exchange between the magnetocaloric effect element and the medium in a reduction period within the demagnetization period.
 4. The thermomagnetic cycle device according to claim 3, wherein the heat transport device stops flow of the medium in the reduction period at a beginning of the demagnetization period.
 5. The thermomagnetic cycle device according to claim 2, wherein the magnetic field modulator is configured to: increase a strength of the external magnetic field in an increasing period within the magnetization period; and decrease the strength of the external magnetic field in a decreasing period within the demagnetization period, and the increasing period is longer than the decreasing period.
 6. The thermomagnetic cycle device according to claim 1, wherein the at least one of the magnetic field modulator and the heat transport device is configured such that the first heat exchange amount is smaller than the second heat exchange amount.
 7. The thermomagnetic cycle device according to claim 1, wherein the at least one of the magnetic field modulator and the heat transport device is switchable between an acceleration operation mode in which the first heat exchange amount is different from the second heat exchange amount and a normal operation mode in which the first heat exchange amount is equal to the second heat exchange amount.
 8. The thermomagnetic cycle device according to claim 7, further comprising a controller that controls the at least one of the magnetic field modulator and the heat transport device, wherein the controller defines a period of the acceleration operation mode which is executed before the normal operation mode.
 9. The thermomagnetic cycle device according to claim 8, wherein the controller defines the period of the acceleration operation mode based on an elapsed time of the acceleration operation mode or an observation temperature related to a temperature of the magnetocaloric effect element.
 10. The thermomagnetic cycle device according to claim 7, wherein the acceleration operation mode includes: a cold storage operation mode in which the first heat exchange amount is larger than the second heat exchange amount; and a heat storage operation mode in which the first heat exchange amount is smaller than the second heat exchange amount, and the at least one of the magnetic field modulator and the heat transport device is switchable between the cold storage operation mode and the heat storage operation mode. 